An engine control module of an internal combustion engine controls the mixture of fuel and air supplied to combustion chambers of the engine. After the air/fuel mixture is ignited, combustion takes place and the combustion gases exit the combustion chambers through exhaust valves. The combustion gases are directed by an exhaust manifold to a catalyst (or “catalytic converter”) and/or other exhaust after treatment systems.
During engine operating periods, such as during startup, combustion gases enter the exhaust system while components of the after treatment system, such as the catalyst, are not yet heated to adequately remove pollutants to meet regulations. Further, during startup, forced induction devices include components, such as turbine wheels, which act as heat sinks, thereby slowing down heating of exhaust system components. Therefore, during startup, the flow of exhaust gas to cool exhaust system components, such as the catalyst, can lead to undesirable emission levels, due to the corresponding lower performance of the catalyst.